1. The Field of the Invention
The present invention relates to an apparatus used in conducting isometric testing of individual muscles, muscle groups or joints in physical and occupational therapy diagnosis, and individual functional capacity assessment in employment evaluations. More specifically, the present invention relates to an improved device used in conducting static lift tests, which improves the range of tests which can be performed and which also improves the portability of the device.
2. State of the Art
Isometric assessment of muscular strength typically involves a maximum voluntary contraction at specific joint angles or functional positions against an unyielding platform or handle connected to a device that measures force. Isometric techniques have been employed extensively in orthopedic, sports, rehabilitation, occupational, and industrial clinics for over four decades. Prior to the vast availability of isometric testing products, muscular strength was clinically assessed by methods of isokinetic testing. Isokinetic testing measures strength throughout a range of motion of a body using a yielding, constant velocity device in connection with a force measuring device. This method of testing has become increasingly less common due to the presence of isometric testing products.
The first of such isometric testing devices were developed in the early 1980s and involved measurement of the maximal force using a cable tension meter or dial gauge. Characteristically, these devices are typically composed of a platform upon which the patient stands while pulling upward on a cable connected to the platform. These types of isometric tests are known as xe2x80x9clift tests,xe2x80x9d and are limited to the assessment of large gross forces at only a limited number of muscle groups.
Isometric lift tests provide valuable information to therapists about the functional capacity of an individual""s strength at large muscle groups and joints. These tests also provide occupational therapists and employers with insight regarding the extent of an employee""s ability to functional in various capacities in the workplace.
Though more advanced isometric testing products have been developed in recent years that are more effectively adapted to allow customized isometric testing of particular muscle groups, the basic model allowing only simple lift tests are still widely used. Such products are relatively easy to use and are relatively inexpensive. However, several disadvantages have been recognized in the basic lift test models.
One disadvantage of the basic lift test model is the weight of the apparatus, which is heavy and difficult to move. The large platform constituting the major weight of the apparatus is thick and heavy so that the patient being tested may exert maximum contraction without the platform to which the cable is attached yielding to the force. The size of the platform was also used to eliminate the risk of mechanical leverage caused by the patient""s exertion from lifting the front of the platform and tipping it backwardxe2x80x94potentially causing the patient to fall. The weight and size of the platform, however, make it difficult for occupational therapists and the like to take the isometric testing device to patients at remote locations. However, smaller and lighter platforms have generally been avoided because of the risk of the platform tipping.
Nevertheless, it is found that the platform need not be so heavy because the nature of a lift test is such that the weight of the individual typically is centered over the point of opposite force exerted by the same individual, preventing the platform from yielding to the opposite force. Thus, the device need not be heavy, large, or difficult to transport. In light of the problems with the prior art, however, there is a need for a device that weighs less and is more easily moved and transported, while still offering sufficient resistance to the opposing force of the patient""s contraction and minimizing mechanical leverage if the patient leans back during the test. Such a device should be more easily transported to on-site evaluations, and could be easily moved or adjusted during actual testing.
Another disadvantage of the basic lift model is the surface area of the apparatus and the consequent space required for its storage. The platform of existing models is typically 30xe2x80x3xc3x9748xe2x80x3, and occupies a significant portion of a typical office floor. The size of the platform occupies a large portion of a closet, and rarely fits into smaller storage spaces. The bulky nature of the platform makes it difficult to store away. This is particularly important for physical therapists and occupational therapists who travel to their patients or to various clinics to conduct testing or treatment. The large platform will not fit in many automobile trunks. Thus, there is a need for a basic lift model that can be conveniently stored away in smaller spaces. There is also a need for an apparatus that occupies less floor space while either being used, stored in the open, or transported.
A further disadvantage of the basic lift model is the inability to accommodate specialized lifts designated by the physician. The prior art contains a single stationary attachment on the platform for the belt to which the opposing force is applied, which limits the range of variation of muscle groups that can be tested while the patient stands in a single position. In other words, for a patient to perform several of the NIOSH standardized lift tests, he must vary his position on the platform to create the appropriate angles and positions. Varying the patient""s position on the platform to conduct multiple NIOSH tests makes repeat testing of the identical test difficult.
Thus, there is a need for the platform to contain an adjustment mechanism that can allow the belt to be positioned along an axis of the platform to accommodate specialized lift tests designated by the physician and that can more easily accommodate repeat testing without changing the position of the patient. A sliding mechanism would allow the patient to remain stationary while the physical therapist or occupation therapist slides the point of the belt attachment along the rail to create a new angle of force exertion. The new angles allow testing of different muscle and joint groups, or to find particular weaknesses long the patient""s range of motion for a particular joint. Of course, other adjustment mechanisms which do not slide could also be used.
In view of the above mentioned disadvantages of the existing devices, it would be an advance in the industry of isometric lift testing devices to provide an apparatus for isometric lift tests, which is easily transportable, relatively light and over comes other disadvantages of the prior art.
It is an object of the present invention to provide a mobile lift system and method of use that improves upon the existing technology of isometric lift test devices.
The above and other objects and advantages of the present invention are accomplished by a mobile lift system having a platform which is generally smaller than the platforms of the prior art lift systems, and an attachment rail that engages the platform.
The platform of the mobile lift system is preferably smaller than the platforms of prior art lift systems, and the attachment rail extends from the platform to enable a point of attachment for the cable used for the isometric test to be positioned away from the platform. The rail may be adjusted relative to or removed from the platform when not in use to reduce the overall dimensions of the mobile lift system. This, in turn, requires less space for storage and allows easier transportation of the apparatus to on-site testing locations.
In accordance with one aspect of the present invention at least bracing member is disposed along the attachment rail. The bracing member is positioned to prevent the patient from lifting the front end of the platform by leaning rearwardly while performing a lift. Preferably, the bracing member will extend down into contact with the surface on which the platform is placed. However, the bracing member could be disposed slightly above that surface so that it only engages the surface one the mechanical leverage caused by the patient is about to cause the front end of the platform to be lifted off the ground.
In accordance with another aspect of the present invention, the mobile lift system includes an attachment member which is adjustable so that it may be positioned at various locations along the attachment rail. The attachment member allows the lower end of a belt or cable used for isometric testing to be moved between a variety of positions along the attachment rail. By simply adjusting the attachment member along the attachment rail, the therapist can test a wide range of lift positions while the patient remains in the same position. These accommodations of the present invention also allow the therapist to perform various tests without moving the position of the patient, which will accommodate accurate repeat tests of the patient in the same position.
In accordance with yet another aspect of the present invention, the attachment rail is ruled and the attachment member is provided with a quick release mechanism that makes adjusting the attachment member along the attachment rail simple and easy. The configuration of the attachment member also locks securely along the attachment rail to ensure safe lift tests. Additionally, by marking the position of the patient on the platform and the location of the slide block assembly along the ruled attachment rail, the therapist can readily repeat tests over a period of time to monitor a patient""s improvement.